Little brothers

Tell me if you've heard this one. There were three brothers... and the youngest, contrary to the normal rules of inheritance and primogeniture, gets the kingdom. Sound familiar? It's the basic plot of many folk tales. But where does it come from? Why the reversal of the established order of things? How far back does it go?
Zeus was King of Heaven. He was also the youngest of Cronus and Rhea's brood of godlings, and the youngest brother of Hades and Poseidon. But in deposing his father, he was following the pattern set by Cronus who was himself the youngest Titan, of six brothers and six sisters. Now gods tend to come in trinities. The male Titans divide nicely into two threesomes : Hyperion, Oceanos and Iapetus; and the alliterative Coeos, Crius and Cronus. It is possible that this was an amalgamation of two separate pantheons - the same trio of gods under different names.
Iapetus has been identified with the biblical Japhet, son of Noah, who is himself a third brother of Ham and Shem, and it is he who is the ancestor of every Greek hero you've ever heard of.
It is not hard, therefore to conceive the possibility that the folktales of the middle ages refer back to the mythology of two millenia previously, giving hope to younger sons everywhere that there may be a kingdom waiting for them.
Goddesses, and women in general, in this misogynistic history, don't get a look in at all.